Re: remove items appearing in both lists

On 2008-07-20, xahlee@[EMAIL PROTECTED]
 <xahlee@[EMAIL PROTECTED]
> wrote:
> Given 2 lists Olist and Clist. I want to remove items that appears in
> both list. How best to do this?
>
> Say,
>
> (setq Olist (list "a" "b" "c" "d" "e"))
> (setq Clist (list "ee" "a" "d" "c" "bb"))
>
> i want the result to be like
>
> (setq Olist (list "b" "e"))
> (setq Clist (list "ee" "bb"))

Since you're assigning to variables, wouldn't this be off-topic in
comp.lang.functional? :)

> order doesn't matter.

 ;; items common to both sets

 (intersection '("a" "b" "c") '("b" "c" "d") :test #'equal)

 -> ("b" "c")

 ;; items in the left set which are not in the right set

 (set-difference '("a" "b" "c") '("b" "c" "d") :test #'equal)

 -> ("a")

You want to remove (via set-difference) from each original list the
intersection of those two lists: